1. Field
The following description relates to a smart grid network, and more particularly, to data transmission in an advanced metering infrastructure (AMI) network.
2. Description of the Related Art
Growing interest in smart grid worldwide motivates the development of smart grid-based power network, enabling energy supplying systems of various suppliers and diversified consumers' systems to be integrated with each other and to respond to and interact with each other in real time. In this regard, an advanced metering infrastructure (AMI) network has gained more attention since it allows two-way communication and integrated management between the energy suppliers and the consumers.
AMI network offers two-way services that provide not only electricity consumption measured by a meter to electricity suppliers but also diversified information from the electricity suppliers to consumers. The electricity suppliers may provide information, such as electricity price, demand response and load control (DRLC) commands, messaging, billing, and distributed energy resource control (DERC) commands to users over the AMI network. Such provided information may help the users to reduce their energy bills by controlling the electricity usage or changing the time of use of electricity.
Such AMI technologies are defined as Smart Energy Profile (SEP), which is a standardized profile created by ZigBee Alliance. SPE defines energy service interface (ESI) for connecting electricity suppliers and consumers over a network, In-Premise Display (IPD) or In-Home Display (IHD) for AMI service display, smart thermostat for temperature control, load control (LC) for energy usage control, a meter for measuring energy consumption, plug-in electric vehicles (PEVs), smart appliances, pre-pay terminals (PPTs), and home energy management systems (HEMS), and other definitions will be expected to be added.
According to SEP, a meter needs to keep recording consumption of energy in intervals of, for example, 15 minutes (at minimum 2.5 minutes and at maximum 24 hours) for at least several months. Time of use tariffs vary from country to country but are generally represented in 15-minute intervals. In addition, customer baseline load (CBL) required for calculating consumption of energy by each customer in connection with real-time pricing is also generally represented in 15-minute intervals.
Interval tables including different types of intervals are used to calculate a charge for energy used up to the present time. It may become general for such interval tables to be delivered to users' devices (ESI, IPD, LC, Meter, PEV, PPT and HEMS) while the devices exchange the interval tables, so as to provide a variety of analytic methods for reducing energy billings, wherein the interval tables show not only energy consumption on an hourly basis, a daily basis and/or a monthly basis, but also the time period in which relatively higher rate is applied due to energy consumption used beyond CBL.
The quantity of data to be transmitted between users and energy suppliers may increase if different types of interval tables should be stored or exchanged for several months. ZigBee communications, as standard communications, may be of low cost and low-power consumption, but have low-capacity memory and low transfer rate. Thus, ZigBee communication devices may be overloaded by the amount of data.
In practice, there have often been demands that a large amount of interval tables which were missing due to unpredictable events, such as communication errors for a long period of time, device reset and blackout, should be transmitted between devices implementing ZigBee technology. In addition, the devices requested electricity suppliers to provide information about energy consumption, tariffs and CBLs related to several months, at the time of start of analysis with HEMS or IPD in an effort to reduce energy bills, which led to a large amount of traffic. Currently, not a large amount of traffic flows over an AMI network since there are not many distributed smart energy (SE) devices, but it is anticipated that the traffic overload would increase as more LC or smart electronic appliances are used.